The non-conventional yeast Kluyveromyces marxianus is an emerging industrial producer for many biotechnological processes. Here, we show the application of a biomass-linked stoichiometric model of central metabolism that is experimentally validated, and mass and charge balanced for assessing the carbon conversion efficiency of wild type and modified K. marxianus. Pairs of substrates (lactose, glucose, inulin, xylose) and products (ethanol, acetate, lactate, glycerol, ethyl acetate, succinate, glutamate, phenylethanol and phenylalanine) are examined by various modelling and optimisation methods. Our model reveals the organism's potential for industrial application and metabolic engineering. Modelling results imply that the aeration regime can be used as a tool to optimise product yield and flux distribution in K. marxianus. Also rebalancing NADH and NADPH utilisation can be used to improve the efficiency of substrate conversion. Xylose is identified as a biotechnologically promising substrate for K. marxianus.

No abstract

Selecting an efficient small set of adjustable parameters to improve metabolic features of an organism is important for a reduction of implementation costs and risks of unpredicted side effects. In practice, to avoid the analysis of a huge combinatorial space for the possible sets of adjustable parameters, experience-, and intuition-based subsets of parameters are often chosen, possibly leaving some interesting counter-intuitive combinations of parameters unrevealed. The combinatorial scan of possible adjustable parameter combinations at the model optimization level is possible; however, the number of analyzed combinations is still limited. The total optimization potential (TOP) approach is proposed to assess the full potential for increasing the value of the objective function by optimizing all possible adjustable parameters. This seemingly unpractical combination of adjustable parameters allows assessing the maximum attainable value of the objective function and stopping the combinatorial space scanning when the desired fraction of TOP is reached and any further increase in the number of adjustable parameters cannot bring any reasonable improvement. The relation between the number of adjustable parameters and the reachable fraction of TOP is a valuable guideline in choosing a rational solution for industrial implementation. The TOP approach is demonstrated on the basis of two case studies.

No abstract

Abstract. There are solutions in the market that enable brand holders to combine their serviceswithother suppliers of goods or services. However, there is no unified technological solutionavailable for e-commerce purchasing object management. Purchasing objects are objects that are generated automatically or manually createdas a result of the transaction, for example, a bus ticket, travel insurance payment, concert ticket orthird party liability insurance. Management of purchasing objects is an important e-commerce process for all involved parties. Now a variety of payment methods and information systems are available in the market that allows generating purchasing objects. E-tickets are an example of the purchasing objects, which are rapidly being introduced for use. Electronic ticket management is increasingly entrusted to mobile devices and applications. Market analysis shows that e-ticket management becomes more complicated because it is related to different systems, applications and interfaces in the transport sector. This study analyses the mobile ticket life-cycle management problems that are being solved in the development of the service providers' mutual integration solution architecture model. The unified public transport service scenario was developed, which consists of purchasing object generation, storing and transporting to service providers, transaction processors and customers. The developed purchasing object management model provides customers with opportunity to manage the financial transaction documents, while service providers will facilitate the document turnover and improve the business process. The proposed model has been piloted on a joint stock company micro-payment system infrastructure, integrating Latvian Railway external services. The study was conducted in the framework of Latvia, and is aimed to improve e-commerce solutions in Latvia.Keywords: e-ticket, m-ticket, e-commerce solution. IntroductionRapid developments in information technology transform the way various businesses are executed. With maturing of the technology and fast distribution of smartphones, more and more businesses go partially or fully mobile. However, business preparation for mobile e-commerce includes an important step -creating mobile service that is convenient for merchants and is user friendly. Data show that in Finland after installation of mobile applications during the next month only 35 % are continued to be used [1].Another important step is to include payment methods that users recognize and can apply, such methods include or are compatible with local internet banks, and use recognised services such as PayPal, Square, Stripe or others. IT companies develop special applications to support mobile payments such as Google Wallet and Apple Pay. These applications allow storing payment data in special protected profile, so whenever the user needs to pay for the product or service, there is no need to re-enter payment information. Such special applications are rather new solutions and still unavailable in man...